Usually, it is less expensive to buy on-line.  But, don't forget that you may have to pay postage on top of that good buy you got.  So, many times, it doesn't make a lot of difference by the time you write the check.  If you have a local hobby shop, you ought to try to give it at least some of your business.  The folks who work there can be an invaluable resource for you, and they will be much more willing to help a good customer than some stranger who walks in off the street looking for help with a broken locomotive he bought on-line or at some big chain store.
OldTimer  

Be careful with the Dremel...what you remove can never be put back.  My tool of choice is a needle file.  You should be able to buy a set at a local hardware store, but if not, Micro-Mark always has them.  www.micromark.com will get you there.
OldTimer

I drive past Deep Creek Lake, Md., often and it always looks very dark green to black to me.    I agree that large rivers, becuase of the amount of sediment they carry, often look muddy brown.  Use colors that look right to you.
OldTimer

Water looks wet because it is highly reflective.  Since you can't look down into a body of water, what we need to model is the reflectivity and color.  Coat the bottom of your stream with a plaster slurry and let it set up fully.  Sand lightly and clean up the dust.  Paint the plaster an earthy color along the bank and feather that into a black or very dark green in the deepest parts.  Allow the paint to dry throughly.  Cover the paint with several coats of clear gloss varnish, making sure that each coat is completely dry before you add the next.  Not a real expensive process.  Hope this helps.
OldTimer

Ken,
Decoder functions are usually associated with lighting effects, but they can control other things as  well, a smoke generator, for example.  The more functions your decoder supports, the more effects you can implement:  ditch lights, flashing strobe, cab light, and Mars light for example.  Your decoder manual will help you get a handle on how to control the functions your decider supports.  Hope this helps.
OldTimer

One of the very first things you should think about is getting your layout off the floor and onto some sort of solid benchwork. 
OldTimer

Often times, new engines come from the factory a little bit "tight."  Try breaking your locomotive in by running it at various speeds, both forward and reverse, for thirty minutes or so.  If you are running on an oval, physically turn the engine around about half way through the process.
OldTimer

Webster,
Could you please let me know the author of the book that suggested drywall for roadbed.  I'll be adding him to my don't buy or recommend list.  Drywall is a horrible material to work with, as anyone who has ever used it for its intended purpose will tell you.   
OldTimer

Kadee sells a number of different screws with drills and taps to match.  The 2-56 screws are commonly used to attach coupler boxes.  At least that's what I use and I'm pretty common.     The #50 drill and 2-56 tap work together to make a threaded hole for the screw.

If you want to electrically isolate a siding, cut one rail (either literally or with an insulated rail joiner and wire a single pole / single throw (SPST) switch (like a light switch) across the gap.  If the siding is double ended, gap the rail at both ends, but you still only need one SPST switch. 
When the switch is open, the siding will be dead.  Close the switch and the siding will be live.

OldTimer

As I recall, the Hi-F drive was the product of the Athearn brain trust.  The rubber band drive let them produce a nice engine for a very resonable price because there were no gears to pay for.  I had a Geep, and the F-7 was also available with rubber bands.  The bodies were the same as the geared version.  I believe that the 2nd generation Athearn RDC's were all Hi-F as well.  The Hi-F units ran a little unevenly but couple two of them together and they would sort of smooth each other out.
OldTimer

You need to build a framed base for the plywood.  I use 1X4's from Lowes....inexpensive and pretty straight.  I put the crossmembers on 16" centers and assemble the whole shabang with utility screws. 
Hope this helps.
OldTimer

If you bend the shank of a coupler that sits too high or too low, the shank will bind in the draft gear box and the coupler will not center properly.  Kadee makes thin fiber washers that can be used between the car frame and trucks to raise a low coupler.  A coupler that's too high is more of a problem.  If the coupler box is a separate piece, it can be removed and shimmed down the required amount.  If the box is cast as part of the underframe, remove it (an Xacto chisel blade works well), replace with a new box and shim as necessary.  If the height difference is about half the thickness of the coupler head, you can use an offset shank coupler.   The underset shank raises the coupler and the overset shank lowers the coupler.  Hope t his helps.
OldTimer

The Kadee #5 coupler is pretty much a de facto standard replacement coupler.  It's made of metal and is very strong.  Look here for instructions for your freight cars.

http://www.kadee.com/conv/pdf/558in.pdf

Locomotives can be a little more of a problem, and Kadee provides extensive information on how to convert literally hundreds of engines.  They make a special conversion kit for the Bachmann F7.  Look here:

http://www.kadee.com/conv/pdf/b26.pdf

Look around the site while you're there.  Kadee invented the magnetically operated knuckle coupler and you can learn a lot from their site.  While you're shopping, get a coupler height gauge to check all your couplers for correct installation, and get some powered graphite to lubricate them.   Hope you find this helpful.
OldTimer

I've been "playing with trains" for over 50 years now and I can tell you that this has always been a tinkerer's hobby.  It just sort of goes with working with lots of moving parts.  Did you ever own an MG?  Nobody asked why MG couldn't build a car that ran right.  Part of the mystique was spending Saturday afternoon tinkering with the carb and the ignition system so you could take your girl out for a spin on Sunday. 

Bachmann could make turnouts that would be derailment proof.  Years ago Tru-Scale made turnouts that had the points and frog fabricated as a solid piece...the whole thing moved very much like the old tinplate turnouts from Lionel.  They almost never caused a derailment, but they didn't look much like the real thing and they were very expensive.  Today, it seems like a lot of manufacturers are trying to be "good enough."  Excellent costs a lot more than good enough and may not perform much better.  I don't use EZ-Track for reasons that have nothing to do with quality, but from what I read, Bachmann has made a product that is good enough.

If you stay with model railroading, you will come to learn how to deal with these little annoyances and take some pleasure from making something that wasn't quite up to snuff work well. 
Just my two cents worth.
OldTimer

You need to do a little homework.  Companies that make DCC starter sets include, but are not limited to, Bachmann, MRC, Digitrax and Lenz.  Google will help you find more.   If you visit these companys' web sites, you can learn about each set's strengths.  You can also read the manuals on line to see which might be the easiest for you to use.  Take notes.

Then I'd go to  a hobby shop or three and see if they can demo any sets for you.  See which throttle is the most comfortable to hold.  Take more notes. 

Do you belong to a MR club?  If so and if the club is running DCC, you might want give extra consideration to the brand the club uses.  Ask your fellow members for their experience.  Guess what...take more notes.

Is cost a consideration?  I know it is for me.  By this time you'll probably be leaning towards a couple of sets.  Pice them out on e-Bay, on-line dealers, and your LHS.  I will tell you that local hobby shops are likely to charge more, but for that extra money, you have the right to expect competent support when you need it.  Take more notes. 

I can't tell you which set to buy, but if you inform yourself about the various sets available, you'll very likely be able to make a decision you can be happy with.  Hope this helps.
OldTimer